Heating indoor pool area

Edward A. (Ed) Carey_3

Rob,

Be very careful when conditioning an indoor pool environment.

You must do this correct or the entire room will turn into a nasty "lab experiment".

You must properly control the pool water temp as it relates to the room air temp, and then adequately remove the humidity.

It can cost more to do this correctly that the pool itself costs. Most HO's do not want to hear that, and talk the contractor into doing a Cheaper" job.

Don't let the homeowner dictate what "they want".

If you do, it will haunt you. Guaranteed.

Good luck,

Ed Carey.

Rob Blair

Heating indoor pool area

I am quoting a job for an indoor pool area. Obviously he wants his tootsies to be warm. I am doing my calcs based on 75 degree air temp, letting the concrete up to 93 degree (bathroom temps). Do you think the air temp is correct? Higher/Lower? Concrete Temp? The total area is 2262 square feet with the pool taking up 700 for a total of 1562 feet heated. Ceilings are way up there, 32 feet to the peak. 58 by 39 inside.

Coming up with 36K btu supplemental. Does the pool water temp count for anything?

Ideas, thoughts.

Thanks,

Rob

Brad White_203

Gene Pool

Hi Rob,

I have done a fair amount of indoor pool design. Call them "Natatoriums", and you can charge more

Most pool air temperatures are warmer than that, usually 80 as a minimum, sometimes 82, 84 or more. What is key is not air temperature but water temperature first.

Your air temperature wants to be at least two degrees more than your water temperature. If they invert, you can make fog. Ask me how I know...

All of your emitters, be they air coils, radiation, radiant slab, have to take into account that they are maintaining a warmer baseline environment. By this I mean, they will be de-rated. Use the de-rating factors with care and check them three times.

Consider a heat pump type air system to dehumidify and heat the pool with the waste heat. If the pool may overheat especially in spring and fall, seek an outside condenser even using an outside pool if they have two. (I did this once. They had some money to spend.)

Don't forget materials and corrosion issues. Also, when you have to up-wash the glass to forestall condensation? Seek flush interior surfaces. Deep window muntins mean condensation where the air cannot directly hit the glass.

There is much more, but keep the principles in mind and ask questions. There is danger lurking if you do not look at the whole picture.

EJ hoffman

Towel driers/warmers

And don't forget to upsell a rack of towel warmers/driers. They will love you for the comfort and also the environment will like that you are saving on the wasted energy of extra laundry waste

Rich L.

Dehimidification

I've worked on a few pool room dehumidification units that are setup to either heat pool water (water cooled condenser) or send the refrigerant outside if the pool temp is satisfied. These commercial units are generally setup to heat the air after dehumidification for cold weather application. If you're in a cold area, I think these units are essential to help control indoor conditions.

Seems like you never get it but try to persuade them to seperate the pool chemical storage area from the mechanical systems for the pool. Pool chemicals eat away at mechanical equipment at an alarming rate. I've seen 5 year old equipment in motels that you would swear is 30 yrs old!

Rob Blair

Radiant Walls

Okay Brad,
Now the contractor is asking about baseboard, supplemental to the floors. I thought that any kind of baseboard, or panel rads would be prone to rust so what about walls? What would be the upper limit for wall temps?

Thanks,

rob

Brad White_202

Radiant Walls

Hi Rob,

The same principles apply for radiant walls as far as temperature is concerned.

Parallel to this, because you are using more surface area, your temperature can be lower for the same heating effect. I mention this because it may be that your floor, alone, may require an uncomfortable temperature, especially for lounging activities.

Remember too, heed the dehumidification aspects well. Heating is a relatively simple part of the total equation and they all work together.

tim smith

Look at company link below. They have been around a long time

desert-aire.com . One thing I would look at, use radiant just as floor warming/supplemental heat. Get a real good dehumidifier with reheat air system. As Brad said, air distribution will be fairly critical to keep place dry. Besides above company, try also dry-air.com All catchy names huh! Do your homework. Tim

Rob Blair

I always thoought that you could run higher temperatures on walls since you are not in direct contact with them?

Rob

[Deleted User]

You can, but...

Finished wall surfaces have limitations too...

It obviously depends upon the finish material. Paint and wall paper for example, have a relatively low operating temperature threshold, compared to say moss rock. Or concrete.

As for condensate on windows, consider heating the windows. It will also completely eliminate the window heat loss as we know it.

www.rgiglass.com

Or, drop me a line and I will send you a PowerPoint White Paper on eliminating condensation on exterior windows.

markeatherton@hotmail.com

ME

Mike Thomas_2

pool cover

If it doesen't have one, an automatic pool cover will make a huge difference in humidity. The pool at 85 degrees will put off a lot of heat, usually more than the room needs. The radiant floor is just to keep the pool deck dry and of course feel real comfy. Automatic cover will reduce evaporation by 70% or more. If they can't go that route, the liquid solar blankets, (a chemical to retard evaporation) will get close to 40%. E-mail if you need more information. We specialize in automatic pool covers and indoor applications.

Stephen C.

Hi Brad,

Hmmm.... interesting connection to the green building thread.

83-84 degree air temps and humidity control issues. What kind of windows would be specified. To upwash the glass, is it best to use some sort of forced air system or is convective radiant heat effective enough. We see plenty of -25 degrees celcius days and nights.

What is it with people and natatoriums that there must plenty of glass?

Tombig_4

Listen young Jedi..

...these warriors speak the truth.

A dehumidification system is a must if the owner doesn't want to replace the whole structure in ten years. They are not cheap but it's a better solution than exhaust/reheat which basically just exhausts all the humid air you they just paid to heat.

DryAire and Desert Aire are two good companies for residential pools. Air conditioning the pool area is a nice bonus when it's 95* outside. I agree that forced air or high temp radiation are needed as second stage heat to keep wall and window condensation to a minimum. Any low temp solution probably won't stratify to the cieling and skylights. Stress the pool cover to ease the load on dehumidification.

In a retrofit job I tore out the 100% outside air reheat and installed a DryAire unit. The owner is handicapped and the pool cover is manual so they leave it off most of the time. Even with that system and the existing perimeter baseboard condensation reared it's ugly head when the OD temps dropped below 5*F. Heat recovery and BB couldn't keep up with the heat loss. When the room temps drop below the pool water temp the pool becomes a big steam kettle with evaporation rates of an inch a day. All the not replaced single pane skylights and every area of wall that was lacking in insulation. Run the exhauster for a while and roll out the cover and RH is back to 50%. Do your homework. Do it once. Do it right.

I might add that our resident guru of all things mechanical, Brad White, steered me through the engineering of that installation, my first dehumid system, and I'm forever grateful. I guess you could say he did my homework for me or at the very least steered in the right direction.

Tom Goebig

Brad White_203

Direct Contact

Mark E. has it right, but I will elaborate on this a bit.

The "direct contact" aspects (i.e. "Hot Foot Potential") is subjective, everyone perceives temperature through the soles of their feet differently.

(Ask anyone who has done Fiji-style corporate bonding training walking on hot coals. Hint: If you can do that and suspend all common sense, you too can get a job the financial sector- yes, I said that

But back to the subject at hand: A body is far more likely to react to/respond to the overall radiant effect of surfaces near it. Every body (everybody) is a radiator. One has to, physiologically, emit radiant heat in order to balance the body's internal temperature.

Your core is in the 98 degree range (everyone again varies, but watch where you put that thermometer, Buck-o), but the skin temperature is between 82 and 86 degrees, variably.

(Take off your jacket or roll up your sleeves, the skin on your arms is likely to be warmer than 88F, but on average, will be 85F if bare to the space for a while.)

That is the magic number, 85F, which is the historical limitation on radiant floor (and wall) temperatures.

Bathe yourself in higher temperatures and your body will react as if heading toward heat stroke. Like a sauna, you can tolerate this for a while, but no one is expecting you will read a novel in the sauna and not suffer (regardless of the quality of the book).

Paul Pollets

Indoor Pools

We use Lifebreath pool dehumidification air handlers when doing the indoor pool room. We also heat the decks with radiant on 6" centers and use an in-line duct heater on the Lifebreath system for supplemental, as required. The environment should be sealed from the rest of the home, especially if chlorine is used. Hardware and door trim should be non-ferrous, preferrably stainless. Engineering the system is very important...Lifebreath provides good info in their design manuals.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Brad White_203

Connection to the Green Building Thread? Man,

you are seeing things... I thought it was that meteor across Saskatchewan, but no... you are seeing Green connections to swimming pools now... Time for an intervention?

Windows... it depends. Single glass is out, that much is certain. Double pane is the minimum but triple pane has some merit. The cost is up there, sure, but having more glass layers (more air spaces really) lowers the temperature at which condensation will form.

Even double and yes triple-glass will condense if not washed with warm dry air. Deep muntins as stated, shield the lower portions of glass above them from up-flowing air. That is why "flush internal systems" are so important.

Now, Low-E glass has to come into the conversation at some point; code requires it in most if not all jurisdictions.

One thing I learned about Low-E glass is that the internal surface temperature of double-pane Low-E glass is not significantly higher than comparable double-pane glass. The additional "R-factor" of the Low-E glass is calculated by taking into account the emissivity of the glass itself on an absorptive object.

"OK, Brad, what the heck are you saying?"

If you measure the interior surface of Low-E and standard glass, side by side, with a contact thermometer (thermistor temperature sensor), the surface temperatures will be essentially equal. Less than half a degree and that can be attributed to other variables such as spotlights, local contact, etc.

What Low-E manufacturers do is figure what the equivalent R-value would be to shield an absorptive body (person or temperature sensitive surface), based on the IR reflective properties of the glass.


In other words, Low-E glass will not change the condensing potential of moisture on the glass.

As for people who insist on that much glass? I have to imagine the notion of swimming outdoors has some appeal. Hey, not my call. Just leave the suits on, unless you fit a certain description, I suppose.

Stephen C.

Thanks Brad.

My obscure connection to the building science thread was as the author stated we should build the best possible buildings and envelope.

Brad White_203

I knew that, Stephen :P

I was just tweaking along with the reference It was not that obscure, at least not as much as I can be.

Mike Thomas_2

Chemicals

If possible get your customer to consider a biaguanide type sanitzer instead of chlorine. Chlorine will eat everything in sight. Baquacil is one good brand name. They had the patent for years and make a good product. Others are out there.